Shred the zucchini in a food processor fitted with the shredding attachment and place in a colander over a large bowl (my preferred method.) Toss with 1 tablespoon kosher salt and allow to drain for 30 minutes. Call your kids to the kitchen so they can watch the next step. Place the zucchini in a kitchen towel and squeeze out as much liquid as possible. There's a ton! Do not add salt to the mixture again. Or shred the zucchini with the potatoes and onions. You will get out more moisture though if you salt them first.
In the bowl of a food processor fitted with the shredding attachment, shred the potatoes and onions. Again, squeeze out as much liquid as humanly possible. Let the mixture rest for a minute and squeeze again.
Place all the shredded vegetables in a large bowl. Add the eggs, salt (do not add if you salted the zucchini early), pepper and bread crumbs to the vegetables and combine well.
Heat the oil (I use olive) in 2 large skillets until hot, but not smoking. An inch of oil will give you the best results.
Using about 2-3 tablespoons of the zucchini-potato mixture, form the latkes into 2 ½-inch pancakes. Flatten slightly and carefully place into the pan. When the edges are brown and crisp, turn them over and continue cooking until deep golden. I usually flatten them slightly in the pan when I flip.
Lay paper towels on a cooling rack or brown paper bag. Transfer the latkes from the pan to the rack. Sprinkle with sea salt if desired. Serve immediately with applesauce or sour cream (if you must).